Earlier quoted context omitted.
it is generally up to you, you can inline them (MIME/base64? in the message) or remotely serve. it'll usually serve remote http pixels for "open tracking" either way though
That's my whole point. I regard such tracking pixels as morally reprehensible. While I know most of my subscribers will disable remote images anyway, quite likely they would think poorly of me for serving them. All the stuff I read about email marketing is all about all the kewel things one can do with email bugs.
Mandrill sets open tracking to 'off' by default[1] and no doubt Sendgrid, et. al make it optional as well. Same goes for link tracking.
(I use Mandrill for emailing dev-related stuff and was also sensitive about this given the demographic/privacy)
https://mandrill.zendesk.com/hc/en-us/articles/205582907-How...